1. Field of the Invention
The present invention relates to low pressure medical balloon articles and to the methodology for making the same, and in particular to a medical balloon useful for in vivo luminal medical procedures.
2. Description of the Prior Art
Various balloon articles are in use for cardiovascular and other medical procedures (such as percutaneous transluminal angioplasty, percutaneous transluminal nephrostomy, urethral dilatation, biliary duct dilatation, percutaneous transluminal renal angioplasty, and the like). Balloons may be utilized for such procedures, that are inflatable or otherwise capable of holding pressure. Pressure levels of balloons may be widely varied, depending on the specific application, and may for example be in a range of from 30-150 pounds per square inch (psi) for higher pressures and balloons and 1-10 psi for low pressure balloons.
Low pressure balloons are there which can hold a pressure on the order of 1-3 psi. Low pressure balloons are typically used for gastrointestinal applications. In other applications, balloons are employed in cardiovascular applications for blocking blood flow, or for removing/blocking a blood clot. In such applications, the balloon is typically bonded to the shaft of a catheter, and after inflation and use, the balloon is readily retracted to an original catheter sleeve shape.
An issue confronting the use of balloon articles for in vivo usage is the asymmetric character of the inflation.
There have been various attempts to shape the balloon so it can be articulated after inflation in vivo for its intended use. For example, in angioplasty applications, clots found in arteries should be held against the artery walls until treated or removed. In prostate treatments it is often desirable to space the prostate from the rectum while treating the same with radiation.
Usually, to achieve the desired inflated shape in low pressure balloons, the balloon material, often latex, is prestretched so as to achieve the desired final shape or the balloon has discrete portions which are overinflated so as to assume a desired shape after insertion and inflation. Another tactic employed is to precure particular selected balloon material so that when inflated, the balloon will assume the precured shape, or to form the balloon with a wall thickness which may vary at different locations in the balloon so as to expand at different rates to achieve different shaped portions in the balloon.
While the resultant balloon would be operational for its intended purpose, each requires an involved fabrication methodology.